Punch for metal sheets



Nov. 28, 1961 E. BARNES 3,010,207

PUNCH FOR METAL SHEETS Filed Aug. 11, 1959 INVENTOR MARCUS E. BARNES Afforper a axmzza j United States Patent 3,010,207 PUNCH FOR METAL SHEETS Marcus E. Barnes, Thornton Township, Cook County, Ill. (RR. 1, Box 484, Lansing, Ill.) Filed Aug. 11, 1959, Ser. No. 833,004 1 Claim. (Cl. 30366) The present invention relates generally to apparatus for piercing metal sheets and more particularly to an improved punch especially suitable for piercing metal sheets arranged in spaced parallel relationship for building construction.

Prior to my invention, where metal building construction called for single sheet siding or roofing, the metal sheets, in smooth or corrugated form, were secured by overlapping their edges and then drilling the overlapped portions of the sheets to provide holes for screw bolt fasteners. Where an air space or insulation was required in the siding or roofing, the sheets were arranged in two spaced apart parallel layers with or without a layer of insulation material, usually in sheet form, therebetween. In the latter type of construction the inner layer of sheets was first fastened to the steel frame of the building with the sheets overlapping. Then the sheets of insulating material were put in place against the inner layer of sheets. The next step involved placing the metal sheets of the outer layer, which were provided with pre-drilled holes, in position against the layer of insulating sheets. Holes were then drilled in the insulating sheeting and the inner metal sheets through the pre-drilled holes in the outer metal sheets. Finally the entire assembly was fastened together by umbrella head screw bolts threaded into the holes and nuts threaded on the bolts. This construction procedure was excessively time-consuming and frequently resulted in the mis-alignment of the bolt holes so that considerable difliculty was encountered in threading the securing bolts through the entire assembly to fasten it together. The use of drills to form the holes in the outer sheets also frequently caused the surface finish of the sheets, which are usually covered with vinyl, to be scratched or marred when the drill was first placed against the sheet before the hole was started.

It is, accordingly, a primary object of my invention to eliminate the aforesaid and other disadvantages involved in the drilling of holes for screw bolt fasteners in sandwich type building construction by providing an improved metal punch whereby an assembly including a pair of sheets arranged in spaced generally parallel relationship, with or without insulation therebetween, may be pierced or perforated quickly and easily in a single operation.

Another object of my invention is to provide a punch of the character indicated which is shaped and dimensioned to provide clearance and relief to the exterior of the punch during its piercing operation and to render the punch capable of speedy and easy withdrawal from the metal sheets after the piercing has been accomplished A further object of the invention is to provide a punch of the character indicated which is so shaped that it rolls inwardly the edges of the hole in the outer sheet during the piercing operation so as to provide a seat for the fastening means to be subsequently inserted through the holes for securing the sheets together.

These and other objects will be more apparent after referring to the following specification and attached drawings, in which:

FIGURE 1 is a plan view of the punch of the invention;

' FIGURE 2 is a perspective view showing the sequential positions of the punch of the invention in piercing a building construction assembly of metal sheets and insulation;

FIGURE 3 is a sectional view taken on the line 'IIIIII of FIGURE 2; and

3,010,207 I Patented Nov. 28, 1961 FIGURE 4 is a sectional view taken on the line IV-IV of FIGURE 2 showing bolting arrangement used to secure the assembly together.

Referring more particularly to the drawing reference numeral 2 designates the shank of the punch of my invention. The shank 2 is elongated and is dimensioned to fit and be retained in the tool bore of a pneumatic impact device such as an air gun 4. The opposite end of the punch is formed into a tapered point 6 which is connected with the shank by means of a stem 8. p

The shank 'of the punch may be round in cross section as shown or any other shape to suit the tool bore of the pneumatic impact device with which it is to be used. The stem 8 and tapered point 6 are round in cross section. A portion 8' of the stern adjacent the shank tapers forwardly of the shank from a maximum diameter, which is greater than the diameter of the base 10 of the tapered point 6, to a diameter which is less than the diameter of the base 10. The remainder of the length of the stem 8 is of uniform diameter less than the diameter of the base 10. A round shoulder 12 is formed at the junction of the shank with the portion 8 of the stem for a purpose which will become apparent as this description proceeds. The relative diameters of the various portion of the punch just described are critical and essential to its successful operation in that they provide the clearance and relief necessary to cause the punch to function speedily and easily and also to render the punch capable of quick and easy withdrawal from the sheets after the piercing operation has been completed.

FIGURE 2 illustrates the sequential movements of the punch in piercing a sandwic type construction assembly consisting of a pair of metal sheets S and S having a sheet L of insulating material therebetween. The position designated A shows the punch just prior to piercing of the outer sheet S. Position B shows the punch after it has pierced the outer sheet. Reference character C designates the position of the punch as the stem passa through the outer sheet S to move the tapered point through the insulation sheet L and partially through the inner sheet S. It will be noted that the opening formed by the point of the punch, because of the diameter of the base of the point, is greater than the diameter of the major portion of the stem so that the stem passes through the outer sheet S and the insulating sheet L with no hindrance. The position designated D shows the position of the punch after both outer and inner sheets and the insulating sheet have been pierced. In position D the larger diameter tapered portion 8 of the stem 8 has passed through the outer sheet S and the rounded shoulder 12 has turned the edges of the hole in outer sheet S inwardly to form a seat for the head of the bolt to be subsequently threaded through the holes to fasten the assembly of sheets and insulating material together. After the assembly of sheets S and S and insulation L has been pierced as just described the tool is easily withdrawn by twisting it slightly and at the same time pulling it out of the pierced hole. The enlarged diameter portion 8' of the stem 8 adjacent the shank 2 is larger in diameter than the base 10 of the tapered point 6, and the portion of the stem adjacent the base of the point 6 is smaller in diameter than the base 10 so that the hole formed in the outer sheet is larger than any portion of the punch which is withdrawn through the hole in the outer sheet after the piercing operation. The slight twist given to the tool as it is withdrawn causes it to pull out easily from the hole in the inner sheet through which only the tapered point of the punch has passed.

As the tapered point of the punch pierces the inner sheet S an extruded flange E is formed around the hole which provides additional gripping surface to the threads of the screw bolt F used to secure the assembly together.

While one embodiment of my invention has been shown and described it will be apparent that other'adaptations and modifications may be made without departing from the scope of the following claim.

I claim:

A punch for piercing a construction of metal sheets arranged in spaced generally parallel relationship which comprises'an integral elongated body formed with a shank at one end, a tapered point at the other end and an intermediate stem connecting said shank and said point, each of said stem and said point having a smooth outer surface, said stem having a portion adjacent the tapered point of less diameter than the maximum diameter of the point and forming a shoulder between the point and the stem, said stern having a portion adjacent the shank of less diameter than the diameter of the shank and forming a shoulder between the shank and the stem, the diameter of said last-named portion of said stem being greater than the maximum diameter of said point, the stem being of such length as to pass through all the sheets of the construction to be punched.

References Cited in the file of this patent UNITED STATES PATENTS 7 1,079,243 Holden "a Nov. 18, 1913 

